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<html>
    <head>
        <title>which selector will be applied</title>
        <link type="text/css" rel="stylesheet" href="style.css">
    </head>
    <body>
        <!-- 特定规则，AND css中最后定义：yellow  -->
        <p class="blue yellow purple red">Android Studio provides the fastest tools for building apps on every type of <em>Android</em> device.</p>
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